326 MORPHOLOGY AND EVOLUTION Others made their way to the Old World and became Catarrhini. Very soon afterwards the Catarrhini separated into tailed Monkeys and tailless Apes. Thus it can be seen that many stages in the evolution of the Primates took place in Eocene times. The Noth-arctidse and Anaptomorphidse were well established, and the former gave rise to the Adapidse whence the Lemurs arose. The Anaptomorphidse gave rise to Tarsius ; and the Monkeys arose from a Tarsioid ancestor. The Monkeys separated into Platyrrhini and forms which became Catarrhini; and the Catarrhini separated into lines which led up to the Simiidae and Cercopithecidae. During recent years the exploration of the Lower Oligocene formations of Egypt by British, American and G-erman palaeontologists has brought to light the remains of many Mammals belonging to various Orders. And the collection of fossils has become known as the Fayum Fauna.* It contains the remains of two Primates of extraordinary interest—Parapithecus and Propliopithecus. The remains of Parapithecus consist of a nearly complete mandible with a full set of teeth, arranged according to the Catarrhine formulafl CtPMf M |. The incisor .teeth are slightly procumbent, and the canine teeth are small. The molar teeth have five conical cusps. The two halves of the mandible unite at a very acute angle, and the symphysis slopes downwards and backwards. The coronoid process is high and pointed and stands well above the condyle on each side. Although neither the skull nor the skeleton has been found one infer from the characters of the mandible and teeth £ * See the works of Schlosser (513) and Andrews (516).